I have sometimes wondered how good these one-way air valves were on bags of freshly #Roasted #Coffee

I packed this #PapaPalheta bag of #CoffeeBeans in the hold of a long-haul flight back from #Singapore and found a clue to the answer.... the low pressure caused the air to escape the bag but then, when the bag was returned into normal atmospheric pressure, the one-way valve did not appear to let the air back in.

Surprisingly effective!
#CoffeeScience #CoffeePhysics